Because it is an energetic pure beta emitter with a half-life on the scale of days (64.1 hr) 90Y is seeing increasing interest as an isotope for use as a radiation source for radioimmunotherapy (RIT). Current processes for obtaining 90Y involve extracting and purifying the 90Y produced by the decay of 90Sr in solution using a liquid-liquid extraction process. The isotope is produced at a centralized location and shipped to users worldwide. The generator proposed here will permit the production of the desired isotope locally in a hospital or regional radiopharmacy where it can be used immediately. Phase I identified two inorganic ion exchange materials that can be loaded with a "cow" of 90Sr and "milked" to produce a carrier-free solution of 90Y ready for immediate use. In Phase II this technology will be further refined and used in the design of a generator capable of delivering a useful quantity of 90Y on a weekly basis in a chemical form suitable for radiopharmaceutical applications. The generator will be fabricated and its efficacy will be demonstrated. The superior long-term stability of the inorganic ion exchanger compared to organic ion exchange materials will be demonstrated. PROPOSED COMMERCIAL APPLICATION: Radioimmunotherapy, where an antibody selectively delivers a radiation source directly to a tumor, is seeing increasing interest as a means of attacking tumors by delivering a therapeutic dose of radiation to the tumor with minimal exposure for other organs. Currently 90Y is produced by a complex multistep process process and supplied from a central source, with clinicians dependent on reliable delivery to have the isotope they need when they need it. The generator proposed here would make 90Y as readily available as 99m Tc is now and greatly increase the use of this valuable therapy. As an alternative, the developed technology could be utilized on a larger scale to simplify the current 90Y production method.